"It’s frustrating, but you’ve got to let it heal itself," said Williams, who felt his back tighten up halfway through Chicago’s first training camp practice and hasn’t returned.

"It’s not going to be a significant amount of time, but I’ve got to get to the point where I can get in and out of my stance."

Starting as backups

Williams is expected to start as a rookie. "Most of the tackles that come out that early play fairly quick," coach Lovie Smith as of the No. 14 overall draft choice.

Still, even if Williams were healthy, he’d be the backup in training camp so far behind John St. Clair. Just as running back Matt Forte, the second-round pick, is practicing with the second team behind career backup Adrian Peterson.

"You start from the bottom," Smith said of the team’s rookies. "It doesn’t matter who it is, if we haven’t seen you, we don’t know enough about you. When you draft a player like Chris, you have an idea where he should end up, but it’s a contact sport. We have to see him in pads and put him through the paces."